The deposition of coal fines in fractures reduces fracture conductivity and hampers efficient coalbed methane production. The results of the multiphase flow visualization experiment indicate that, at low flow rates, fines primarily deposit at the bottom of fracture. At medium flow rates, they exhibit finger-like migration patterns. At high flow rates, some fines initially transported out, but later they tend to form agglomerates. Fine coal fines migrate through suspension and rolling, while medium coal fines form filter cakes both inside and outside the fractures, and coarse coal fines block gas–water flow by forming filter cakes at the fracture fronts. Smaller particle sizes result in higher fines production. The output of coal fines peaks at concentration 4% before declining. Higher concentrations promote the formation of filter cake; however, gas–water injection can effectively clear these blockages. Multiple forces drive fines migration, with capillary forces playing a significant role in this process. The initiation velocity decreases with increasing particle size, but it rises again at a particle size threshold of 22 μm. In the early stages, fines are more influenced by adhesion forces, but gravity prevails as particle size grows. At flow rates between 0.2 and 0.29 cm/s, fines ranging from 0.4 to 52.44 μm are discharged from the coal seam. The results provide insights into coalbed methane production during gas–water flow.

Based on the basic geological data and production data of coalbed methane wells in the Shouyang Block, the characteristics and influencing factors of coalbed methane well production were analyzed, and the primary controlling factors were identified by the grey correlation method. The results show that the average daily gas production of the coalbed methane wells in the study area for the single mining of No. 15 coal ranges from 0 to 604.34 m³/d, with an average of 116.82 m³/d. The overall average gas production is relatively low, with only 7 of the 42 wells having an average gas production greater than 200 m³/d. Gas production tends to increase as the gas content increases. There is a significant positive correlation between gas saturation and average gas production. Burial depth and coal seam thickness also show a positive correlation with average gas production. On the other hand, there is a negative exponential relationship between average gas production and critical desorption pressure. Permeability, as determined by well tests in the area, exhibits a negative correlation with the gas production of coalbed methane wells. The correlation between gas production and the mean three-dimensional stress is weak. As the fractal dimension D value of fractures increases, gas production decreases. A smaller difference in horizontal principal stress is more favorable for the formation of network fractures, facilitating reservoir fracturing and resulting in better reconstructive properties. Moreover, an increase in the sand–mud ratio leads to a decrease in average gas production. The correlation between fault fractal dimension and average gas production is weak. The grey correlation method was employed to determine the controlling factors of coalbed methane production in the study area, ranked from strong to weak, as follows: coal thickness > fracture fractal dimension D value > gas saturation > coal seam gas content > horizontal stress difference coefficient > permeability > critical desorption pressure > mean value of three-dimensional principal stress > coal seam burial depth > sand–mud ratio > fault fractal dimension.

The Shouyang Block was selected as the research subject. Comprehensive analysis was conducted using coalbed methane (CBM) well production data, geochemical test data on water produced from the coalbed methane well, and fundamental geological information. The findings reveal the water dynamics in the Shouyang Block are characterized by weak groundwater runoff or retention in most areas. The groundwater head height exhibits a gradual decrease from the north to south, which is closely associated with the monoclinic structure of the Shouyang Block. Overall, water production is relatively high. As the average water production increases, the average gas production gradually decreases. A concentration of high water production wells is observed in the northern part of the Shouyang Block, which gradually increases towards the southeast direction. A comprehensive analysis was conducted on the factors influencing water production, including total water content of coal seams, coal seam porosity, groundwater stability index, groundwater sealing coefficient, D value of the fracture fractal dimension, fault fractal dimension, and sand–mud ratio. The correlation degree was calculated and ranked in order of magnitude through grey correlation analysis. The order of factors that influence water production, from strongest to weakest, is as follows: sand–mud ratio > porosity > fractal dimension of fault > fracture fractal dimension D value > groundwater sealing coefficient > groundwater stability index > total water content of coal seams. The dissolution amounts of carbonate and sulfate are both small, and the water source may mainly come from the sandstone aquifer. Attention should be paid to the distribution and lithological combination of sandstone aquifers in coal-bearing strata in the future exploration and development process of the Shouyang Block. This will help to avoid the potential influence of fault structures and enable the identification of favorable areas for low water and high gas production.